The invention relates to a mechanism for supporting an arm rest on a chair to allow for both a pivotal movement of the arm rest with respect to a frame of a chair back and a disconnection of the arm rest from the frame of the chair back. The invention also relates to a multi-purpose cushioning insert for the supporting mechanism, which holds the arm rest in any adjusted pivotal position, provides a labyrinth path for removal of the arm from the chair back, and provides noise suppression for the pivoting mechanism.
It is known to provide pivoting arms for chair backs that are attached thereto by means of a rod that provides a pivoting axis for the arm. Vaughn, et al U.S. Pat. No. 3,357,740; Chang U.S. Pat. No. 4,707,032; and Wallace, et al U.S. Pat. No. 4,040,665 each show such a rod mechanism wherein a pin on the rod passes with the rod through a keyhole opening, in a chair back frame member. Because of the keyhole opening the arm can only be inserted or withdrawn from the chair back frame in a single specific relative angular position of the pin and keyhole. That is, the pin must be aligned with the slot portion of the keyhole slot. These patents also show that the pivotal movement of the arm with respect to the chair back frame can be limited by having the pin abut a stop to limit the extent of rotation of the shaft relative to the frame of the chair back.
The above type of rod-pin and keyhole mountings suffer from the problems that such a mounting mechanism is noisy in operation, does not retain the arm in a desired set inclination, and also does not keep the arm from becoming easily disconnected from the chair back frame as it is rotated from one position to another.
It is an object of the instant invention to avoid the above problems by providing a mounting mechanism that offers a quiet operation, an ability to hold the arm at desired locations, and also provides a mechanism for inhibiting disconnection of the arm during its rotation.
These objects are obtained by providing a deformable insert and mounting bracket for pivotally attaching an arm to a chair back frame. The deformable insert has a labyrinth path for a pin on the pivoting shaft of the arm to follow during assembly of the arm to the frame to inhibit unintentional removal of the arm during pivotal operation of the arm. Passageways of the path compressingly engage the pin to hold the arm in any position.
Here an insert for the mounting bracket of the frame of the chair back. An end of the pivot shaft and the pin on the arm are axially inserted through a keyhole in one wall of the bracket and pushed into the insert which is retained in the bracket. The insert has a central bore to allow passage of the shaft completely therethrough so that the insert end of the shaft can be pushed completely through the insert and into a circular hole on an opposing wall of the bracket. This circular hole is in alignment with the circular hole of the keyhole in the bracket. The position of the pin and the shaft with respect to the insert and mounting bracket is retained inside the insert during this push insertion operation. The insert cooperates with the pin on the shaft to provide limit stops for arresting relative angular movement of the arm and the frame of the chair back during the arm's normal pivotal movement.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.